Kent T. Yamaguchi

Clay-shoveler's fracture equivalent in children.

Study Design. Case report and literature review. Objective. This article reports 2 cases of clay-shovelers fracture equivalent in children presenting acutely after participation in sports. Summary of Background Data. The clay-shovelers fracture in adults is an avulsion fracture of the lower cervical or upper thoracic spinous process. To our knowledge, this is the first report in English literature on soft-tissue avulsion injury of the spinous process in children presenting with history and symptoms similar to clay-shovelers fractures. Methods. Retrospective review of 2 cases. Results. A 14-year-old baseball player and a 16-year-old wrestler experienced acute posterior neck pain after participation in sports. Both patients presented with a history and physical examination suggestive of clay-shovelers fracture but showed no evidence of injury on radiographs. Subsequent magnetic resonance images demonstrated an acute soft-tissue avulsion of the spinous process at C7 in 1 patient and T2 in the other. With nonoperative therapy, both patients returned to sports by 4 months, with occasional, intermittent discomfort a year after injury, which did not limit any activities. Conclusion. In adolescents, if the history and physical examination are consistent with a clay-shovelers fracture, but radiographs are normal, magnetic resonance imaging may be indicated to diagnose a soft-tissue avulsion.

Surgical technique for balancing posterior spinal fusions to the pelvis using the T square of Tolo.

Background: Correcting pelvic obliquity and improving sitting balance in neuromuscular scoliosis often requires fixation to the pelvis. We describe the use of a T square instrument to assist intraoperatively in evaluating the alignment of these curves and achieving balance in the coronal plane. Methods: The T square instrument was constructed with a vertical limb perpendicular to 2 horizontal limbs in a T formation. At the conclusion of the instrumentation and preliminary reduction maneuvers, the T square was positioned with the horizontal limbs parallel to the pelvis and the vertical limb in line with the central sacral line. If the spine and pelvis were well balanced, fluoroscopic images demonstrated that the superior aspect of the vertical limb of the T square was crossing the vertebral body of T1. If this was not shown, then some combination of compression, distraction, or a change in the contouring of the rods was performed until this balance was achieved. Results: In this series, we describe case examples in which the T square has been successfully used to aid in achieving balance in the coronal plane. This technique helps to overcome the challenges with positioning and imaging often encountered in managing these long, rigid curves. The T square is a useful adjunct in balancing posterior spinal fusions and evaluating the correction of pelvic obliquity in cases of neuromuscular scoliosis. Conclusions: This novel, yet simple, T square technique can be used for any method of posterior spinal fusion with lumbopelvic fixation to assist in the intraoperative evaluation and achievement of balance in the coronal plane and has become routine at our institution. Level of Evidence: IV

Assessment of Lowest Instrumented Vertebra Tilt on Radiographic Measurements in Lenke ''C'' Modifier Curves Undergoing Selective Thoracic Fusion in Adolescent Idiopathic Scoliosis

STUDY DESIGN Multicenter, retrospective cohort study. OBJECTIVES The purpose of this study is to determine how the amount of residual lowest instrumented vertebra (LIV) tilt correlates with radiographic measurements. When performing a selective thoracic posterior spinal fusion for adolescent idiopathic scoliosis (AIS), the LIV may be tilted into the lumbar curve or made horizontal. METHODS This is a multicenter retrospective study of 33 consecutive patients with AIS, Lenke types 1 to 4, lumbar modifier C, and a minimum follow-up of 2 years, who underwent selective thoracic posterior spinal fusions. Measurements obtained from pre- and postoperative radiographs were correlated with postoperative LIV tilt. RESULTS At final follow-up, less postoperative LIV tilt significantly correlated with less thoracic apical translation (p =.023) when controlling for the position of the LIV relative to the stable vertebra and preoperative thoracic and lumbar curve flexibility. LIV tilt was not significantly associated with thoracic Cobb angle, lumbar Cobb angle, lumbar apical translation, coronal balance, sagittal balance, or the amount of correction obtained compared to their preoperative measurements (p >.05). CONCLUSION Decreased LIV tilt was significantly associated with decreased thoracic apical translation. LIV tilt did not significantly correlate with coronal balance or any other radiographic measurement. We caution that these findings may only be applicable in C modifier curves and when the correct LIV is chosen. LEVEL OF EVIDENCE Level III, Therapeutic study.STUDY DESIGN Multicenter, retrospective cohort study. OBJECTIVES The purpose of this study is to determine how the amount of residual lowest instrumented vertebra (LIV) tilt correlates with radiographic measurements. SUMMARY OF BACKGROUND DATA When performing a selective thoracic posterior spinal fusion for adolescent idiopathic scoliosis (AIS), the LIV may be tilted into the lumbar curve or made horizontal. METHODS This is a multicenter retrospective study of 33 consecutive patients with AIS, Lenke types 1 to 4, lumbar modifier C, and a minimum follow-up of 2 years, who underwent selective thoracic posterior spinal fusions. Measurements obtained from pre- and postoperative radiographs were correlated with postoperative LIV tilt. RESULTS At final follow-up, less postoperative LIV tilt significantly correlated with less thoracic apical translation (p = .023) when controlling for the position of the LIV relative to the stable vertebra and preoperative thoracic and lumbar curve flexibility. LIV tilt was not significantly associated with thoracic Cobb angle, lumbar Cobb angle, lumbar apical translation, coronal balance, sagittal balance, or the amount of correction obtained compared to their preoperative measurements (p > .05). CONCLUSION Decreased LIV tilt was significantly associated with decreased thoracic apical translation. LIV tilt did not significantly correlate with coronal balance or any other radiographic measurement. We caution that these findings may only be applicable in C modifier curves and when the correct LIV is chosen. LEVEL OF EVIDENCE Level III, Therapeutic study.

Prediction of ACL Force Produced by Tibiofemoral Compression During Controlled Knee Flexion: A New Robotic Testing Methodology

Tibiofemoral compression force (TCF) is an important component of anterior cruciate ligament (ACL) injuries. A new robotic testing methodology was utilized to predict ACL forces generated by TCF without loading the ligament. We hypothesized that ACL force, directly recorded by a miniature load cell during an unconstrained test, could be predicted by measurements of anterior tibial restraining force (ARF) recorded during a constrained test. The knee was first flexed under load control with 25N TCF (tibia unconstrained) to record a baseline kinematic pathway. Tests were repeated with increasing levels of TCF, while recording ACL force and knee kinematics. Then tests with increasing TCF were performed under displacement control to reproduce the baseline kinematic pathway (tibia constrained), while recording ARF. This allowed testing to 1500N TCF since the ACL was not loaded. TCF generated ACL force for all knees (n=10) at 50° flexion, and for 8 knees at 30° flexion. ACL force and ARF had strong linear correlations with TCF at both flexion angles (R2 from 0.85 to 0.99), and ACL force was strongly correlated with ARF at both flexion angles (R2 from 0.76 to 0.99). Under 500N TCF the mean error between ACL force prediction from ARF regression and measured ACL force was 4.8 ± 7.3 N at 30° and 8.8 ± 27.5 N at 50° flexion. Our hypothesis was confirmed for TCF levels up to 500N, and ARF had a strong linear correlation with TCF up to 1500N TCF.

Trends and Complications in Open Versus Endoscopic Carpal Tunnel Release in Private Payer and Medicare Patient Populations

Purpose: The purpose of this study was to report trends, complications, and costs associated with endoscopic carpal tunnel release (ECTR) and open carpal tunnel release (OCTR). Methods: Using Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision (ICD-9) codes, patients who had open versus endoscopic carpal tunnel release (CTR) were identified retrospectively in the PearlDiver database from both the Medicare and Humana (a private payer health insurance) populations from 2005 to 2014. These groups were then evaluated for postoperative complications, including wound infection within 90 days, wound dehiscence within 90 days, and intraoperative median nerve injury. We also used the data output for each group to compare the cost of the 2 procedure types. Data were analyzed via the Student t test. Statistical significance was set at P < .05. Results: A significantly lower percentage of patients in the endoscopic CTR group had a postoperative infection (5.21 vs 7.97 per 1000 patients per year, P < .001; 7.36 vs 11.23 per 1000 patients per year, P < .001) and wound dehiscence (1.58 vs 2.87 per 1000 patients per year, P < .001; 2.14 vs 3.73 per 1000 patients per year, P < .05) than open CTR group in the Medicare and Humana populations, respectively. Median nerve injury occurred 0.59/1000 ECTRs versus 1.69/1000 OCTRs (Medicare) and 1.96/1000 ECTRs versus 3.72/1000 OCTRs (Humana). Endoscopic CTR cost was more than open CTR for both the Medicare population (

Effects of Proud Large Osteochondral Plugs on Contact Forces and Knee Kinematics: A Robotic Study

1643 vs

Effects of Anterior Closing Wedge Tibial Osteotomy on Anterior Cruciate Ligament Force and Knee Kinematics

1015 per procedure, P < .001) and Humana population (

ACL Force and Knee Kinematics After Posterior Tibial Slope-Reducing Osteotomy

1928 vs

Acute and Rapid Development of Spontaneous Spinal Epidural Hematoma Associated with Combined Aspirin-Dipyridamole Therapy

1191 per procedure, P < .001). Conclusions: In both the Medicare and private insurance patient populations, endoscopic CTR is associated with fewer postoperative complications than open CTR, but is associated with greater expenses.

Arthroscopic Delivery of Injectable Bone Graft for Staged Revision Anterior Cruciate Ligament Reconstruction

Background: Osteochondral allograft (OCA) transplantation is used to treat large focal femoral condylar articular cartilage defects. A proud plug could affect graft survival by altering contact forces (CFs) and knee kinematics. Hypothesis: A proud OCA plug will significantly increase CF and significantly alter knee kinematics throughout controlled knee flexion. Study Design: Controlled laboratory study. Methods: Human cadaver knees had miniature load cells, each with a 20-mm-diameter cylinder of native bone/cartilage attached at its exact anatomic position, installed in both femoral condyles at standardized locations representative of clinical defects. Spacers were inserted to create proud plug conditions of +0.5, +1.0, and +1.5 mm. CFs and knee kinematics were recorded as a robot flexed the knee continuously from 0° to 50° under 1000 N of tibiofemoral compression. Results: CFs were increased significantly (vs flush) for all proudness conditions between 0° and 45° of flexion (medial) and 0° to 50° of flexion (lateral). At 20°, the average increases in medial CF for +0.5-mm, +1-mm, and +1.5-mm proudness were +80 N (+36%), +155 N (+70%), and +193 N (+87%), respectively. Corresponding increases with proud lateral plugs were +44 N (+14%), +90 N (+29%), and +118 N (+38%). CF increases for medial plugs at 20° of flexion were significantly greater than those for lateral plugs at all proudness conditions. At 50°, a 1-mm proud lateral plug significantly decreased internal tibial rotation by 15.4° and decreased valgus rotation by 2.5°. Conclusion: A proud medial or lateral plug significantly increased CF between 0° and 45° of flexion. Our results suggest that a medial plug at 20° may be more sensitive to graft incongruity than a lateral plug. The changes in rotational kinematics with proud lateral plugs were attributed to earlier contact between the proud plug’s surface and the lateral meniscus, leading to rim impingement with decreased tibial rotation. Clinical Relevance: Increased CF and altered knee kinematics from a proud femoral plug could affect graft viability. Plug proudness of only 0.5 mm produced significant changes in CF and knee kinematics, and the clinically accepted 1-mm tolerance may need to be reexamined in view of our findings.